Noise event measures for road traffic

How should noise events in road traffic noise be measured? This paper reports the performance of a set of algorithms that detect noise events in time histories of road traffic noise in the population of acoustic conditions found near roadways. The latter was obtained through simulation of 500 different road traffic noise time histories using a comprehensive range of traffic flow, traffic composition, and propagation distance, conditions in unshielded locations near roadways. The initial set of algorithms tested was developed by systematically expanding on threshold-based algorithms described in the literature, then excluding those that were unreliable. The finding was that the NA50 and NA55 (detecting when road traffic noise exceeded 50 dB and 55 dB respectively), and the NAL50E10 (detecting when the traffic levels exceeded L50 + 10 dB) can all be considered for practical application as event detection indicators. All apply to measurement of indoor events with the windows of the dwelling open. The primary criterion for selection as supplementary indicators (and others in the same clusters that could substitute for them) was their non-monotonic relationship with the LAeq, The traffic and distance conditions under which these event-based measures could potentially be useful supplementary indicators is identified.Griffith Sciences, Griffith School of EnvironmentFull Tex

Auditieve perceptiemodellen voor het efficient analyseren van omgevingsgeluid

Overheden en onderzoeksinstellingen maken steeds vaker gebruik van sensornetwerken voor het gedistribueerd meten van stedelijk omgevingsgeluid. Individuele meettoestellen worden steeds sneller en intelligenter, en laten vaak toe om het geluid ter plaatse te analyseren of zelfs te streamen naar een centrale databank. Een dergelijk meetnetwerk met soms tientallen meeteenheden genereert echter een reusachtige hoeveelheid gegevens. Om deze gegevens efficiënt te analyseren zijn daarom nieuwe technieken noodzakelijk. In deze lezing zullen een aantal computationele modellen, gebaseerd op de menselijke auditieve perceptie, dewelke voor dit doel aan de onderzoeksgroep akoestiek van Universiteit Gent worden ontwikkeld, worden toegelicht. Deze modellen laten toe om specifieke geluiden die mogelijk de aandacht trekken en typisch zijn voor een bepaalde locatie, te selecteren en in detail te analyseren. Daarnaast kunnen dergelijke perceptiemodellen, in combinatie met auralisatie-technieken, in de toekomst ook worden gebruikt bij het ontwerp van stedelijke geluidslandschappen

Measurement of noise events in road traffic streams: initial results from a simulation study

A key question for road traffic noise management is whether prediction of human response to noise, including sleep quality, could be improved over the use of conventional energy equivalent, or percentile, measures, by accounting for noise events in road traffic streams. This paper reports initial results from a noise-events investigation into event-based indicators over an exhaustive set of traffic flow, traffic composition, and propagation distance, conditions in unshielded locations in proximity to roadways. We simulate the time-varying noise level histories at various distances from roadways using a dynamic micro-traffic model and a distribution of sound power levels of individual vehicles. We then develop a comprehensive set of noise event indicators, extrapolated from those suggested in the literature, and use them to count noise events in these simulated time histories. We report the noise-event algorithms that produce realistic, and reliable, counts of noise events for one-hour measurement periods, then reduce redundancy in the indicator set by suggesting a small number of representative event indicators. Later work will report the traffic composition and distance conditions under which noise event measures provide information uncorrelated with conventional road traffic noise indicators — and which thus may prove useful as supplementary indicators to energy-equivalent measures for road traffic noise

The effect of traffic flows on urban soundscape dynamics and how to analyze it

Subjective evaluation of soundscapes considers without a doubt the change in amplitude and frequency of the acoustic signal over time. The urban environment can make these soundscape dynamics become rather complex and interesting. In this paper we investigate how traffic flows, quite often the main source of noise in urban an suburban environments, influence the dynamics of the soundscape at intervals of the order of a few seconds to minutes. A model for dynamical traffic noise prediction is presented. Novel descriptors based on the power spectrum of noise level fluctuations allow us to show, using static maps, how the dynamics evolve in side streets, on squares etc